There is generally known that a lamination factor (density) of a winding is increased by winding a plurality of wire rods instead of a single wire rod.
A winding apparatus disclosed in Japanese Unexamined Patent Publication No. 2003-204659 is arranged in such a manner that the winding apparatus is provided with a nozzle in which a plurality of guide holes are formed for inserting wire rods therein and this nozzle is traveled around each tooth (winding core) to form a bundle made of a plurality of the wire rods reeled out from the respective guide holes, which is wound around each tooth of the stator.
A winding apparatus disclosed in Japanese Patent No. 2701441 is constructed in such a way that a nozzle itself rotates in synchronization with travel of the nozzle around a winding core, thereby preventing wire rods from being twisted.